This application is a continuation-in-part of U.S. Pat. Ser. No. 07/707,709, filed May 30, 1991.
1. Field of the Invention
The present invention relates to devices for preventing forced entry into a home or other building through a window, and is specifically applicable to windows of the type having a sash which slides within a frame set in the wall of the building.
2. State of the Art
Windows are a favored means of unwanted entry into structures, as they present far less of a challenge to burglars than doors. Moreover, windows may normally be found in unlighted or otherwise hidden portions of a structure's exterior, and so present an excellent opportunity for unobserved entry.
A window type which presents particular security problems is the so-called "sliding" window, in which a rectangular sash comprising upper and lower horizontal rails and right- and left-hand vertical struts encompass a window pane, the sash being laterally moveable in upper and lower horizontal tracks in a window frame, which also includes vertical side tracks extending between the upper and lower tracks. In either case, it is common for window manufacturers to include a snap-type or pivot-type catch which, when the window is completely closed, prevents horizontal sash movement.
The problem with these prior art catches lies in an inherent design flaw in sliding windows which is intentionally built in by manufacturers for ease of window assembly as well as for ease of sash removal for cleaning of the exterior surface of the window pane and screen installation. This flaw resides in the excess clearance or gap between the top and bottom window frame tracks, which is necessary to permit the sash to be inserted upwardly into the top track at a slight angle to the vertical, tilted to a vertical position, and dropped into the lower track to its normal operating position. The same excess clearance or gap permits a burglar to insert a hook under the lower rail of a moveable sash, or even (in cheaper windows) to merely press upwardly on the window pane with his hands and rotate the sash bottom toward the interior of the building, lower the top sash rail out of the top track, and remove the sash from the window.
Aftermarket security devices commonly do not address this type of unwanted entry, as they comprise locking bars pivoted to the frame at one end and resting in a yoke secured to the sash at the other, spring-loaded horizontal locking bars, clips which grip the track walls, or simply a length of broom handle or other piece of wood sized to fit the track in which the sliding sash rides when the sash is in its closed position. Other devices, which may prevent sash removal, are generally more complex, permanently installed and require drilling into the sash, the frame, or both, for installation. In addition, many of the more sophisticated devices on the market include keyed locks which present safety problems should the window be locked and the occupant of the room be lacking the key in event of a fire, preventing exit from the room.